This invention relates to the emission-spectroscopical testing of metallic samples in which a spark spectrum is produced between a metallic sample and a counter-electrode and is imaged onto a grating, in which the evaluation of the intensities of the spectral lines follows the production of an inert gas atmosphere and the pre-spark period.
The invention is concerned with stationary apparatuses which can also be designated as "quantometers" for the emission-spectroscopical or spectro-analytical testing of metallic samples. These tests are generally carried out in such a manner that initially the metallic samples are abraded on the surface so that a metallic surface is exposed. After placing the metallic sample in the stationary analytical apparatus, an inert gas atmosphere is produced, a discharge is then induced between the exposed surface of the metallic sample and a counterelectrode during the so-called pre-spark period, so that a substantially steady condition is established on the surface of the sample during the spark discharge. The pre-spark period is followed by the integration period, during which the amounts of charge, which are proportional to the intensities of the spectral lines, are integrated and subsequently evaluated. The spark spectra are produced, among other methods, by means of unipolar discharges, to which this invention refers in the following sections.
During a discharge, material vaporizes on the surface of the sample materials and is precipitated in part onto the counterelectrode. Since this can lead to faulty test results, the counterelectrode must be cleaned mechanically from time to time. This mechanical cleaning, however, is too cumbersome if the entire spectro-analytical testing is to occur fully automatically and within a short period of time.